feat: add scrollable and pinned leading/trailing support to NavigationRail (#6356)

* fix: make icon property mandatory in NavigationRail destination

* feat: add pinning and scrollable options to NavigationRail

* add tests

* delete test_control_isolated.py, and move its contents to test_control.py

* Move skills to .agents directory and add AGENTS.md

Rename .codex/skills/* to .agents/skills/* to relocate skill definitions without content changes (100% similarity). Add AGENTS.md documenting that skills live in `.agents/skills`, and add CLAUDE.md as a symlink to AGENTS.md.

* Use :attr: references in NavigationRail docs

Replace bracketed inline references with Sphinx-style :attr:`...` cross-references in sdk/python/.../navigation_rail.py docstrings. This clarifies attribute links for documentation tooling (e.g. selected_icon, leading, trailing, destinations, pin_leading_to_top, pin_trailing_to_bottom) and improves rendering in generated docs. Only docstring text was changed.

* Strip /index suffix from xref routes for folder-based doc pages

Pages like controls/navigationrail/index.md were generating xref
URLs ending in /index (e.g. /docs/controls/navigationrail/index)
instead of the clean /docs/controls/navigationrail that Docusaurus
actually serves. Strip the /index suffix when building page routes.

* Add changelog entry for NavigationRail scrollable/pinned support

Record the new scrollable, pin_leading_to_top, and pin_trailing_to_bottom
properties under 0.85.0 New features, crediting @ndonkoHenri and linking
to #1923 and #6356.

* Add macOS tooltip golden images

Add two golden images for macOS tooltip integration tests: tooltip_shows_on_hover.png and tooltip_custom_properties_on_hover.png under sdk/python/packages/flet/integration_tests/controls/core/golden/macos/control. These images are used to validate tooltip rendering/appearance on hover.

---------

Co-authored-by: Feodor Fitsner <feodor@appveyor.com>

Author: ndonkoHenri

…-flet-control-integration-tests/SKILL.md …-flet-control-integration-tests/SKILL.md.codex/skills/create-flet-control-integration-tests/SKILL.md renamed to .agents/skills/create-flet-control-integration-tests/SKILL.md .codex/skills/create-flet-control-integration-tests/SKILL.md renamed to .agents/skills/create-flet-control-integration-tests/SKILL.md

@@ -77,4 +77,3 @@ If a dialog mutates existing controls and calls `page.update()`, convert it to:
   - `raw = getattr(troute, "id", None)` then `isinstance(raw, str)` before `int(raw)`.
 - **`controls=[*[...], ...]` can confuse type checkers** with components:
   - build lists in two steps and annotate/cast, or return raw controls from non-component factories.
-